Welding High Strength Aluminum

Of course the high strength aluminums are in a heat treated condition when looking at their highest yield strengths.

Then 6061 is popular with machine shops because it machines well and because it is easily available. It is often welded but it is not the best welding aluminum and it is not the highest strength aluminum. The yield strength is 50,000. (When aftermarket fabricators say that something is billet they usually mean machined from 6061.)

And 7075 is famous for strength but it does not weld very well. The yield strength is 76,000 !

But don't forget about 2024 and it does not weld very well. The yield strength here is 67,000.

And so here are some high strength aluminum alloys that are better for welding:

2219, yield strength 66,000
2519, yield strength 66,000
7003, yield strength 50,000
7005, yield strength 51,000
7039, yield strength 58,000

But each aluminum alloy requires a certain type of filler material for welding
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I found some aluminum machinability ratings:

2024, 70%
6061, 50%
7075, 70%
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Of course most aluminum is TIG welded or MIG welded
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Oh, the subject of cast aluminum wheels versus forged aluminum wheels often comes up. The consumer yawns and buys the less expensive wheel.

But to understand the difference between cast aluminum and forged aluminum then go compare steel to cast iron. See, both steel and cast iron are iron with carbon but steel is about triple the strength of cast iron.

Now some cast aluminum wheels are spin cast while other cast aluminum wheels are flow formed
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Oh, the subject of cast aluminum wheels versus forged aluminum wheels often comes up. The consumer yawns and buys the less expensive wheel.

But to understand the difference between cast aluminum and forged aluminum then go compare steel to cast iron. See, both steel and cast iron are iron with carbon but steel is about triple the strength of cast iron.

Now some cast aluminum wheels are low pressure cast, some cast aluminum wheels are spin cast, while other cast aluminum wheels are flow formed
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Lamborghini's, Ferrari's, the Audi R8, and the 2006 Ford GT's have a chassis of extruded aluminum. But those extruded aluminum pieces tie into die cast aluminum bulkheads. But hopefully, what they call die cast is what I call hot forged.

The C7 Corvette has a chassis with hydroformed aluminum channels that run from the front suspension to the rear suspension in one piece. However, the run from the rocker panel to the rear suspension looks like a minor tie as there is a large rear bulkhead and that is die cast aluminum
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Aluminum doesn't hold up to stress cycles as well as steel does.

So when aluminum is used as a vehicle frame or chassis it is often used in large cross sections turned tall-wise. Then the very stiff frame mitigates the problem of stress cycles. The weight advantage of aluminum after using very large cross sections can be as little as a 5% to 7%
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Aluminum ? The new BMW i3 has a carbon fiber tub and then aluminum subframes that run from carbon fiber bulkheads in the tub to the suspension points. Of course those so-called subframes are also primary chassis and thus just a change of material. But the new process of making carbon fiber parts is something like injection molding and so carbon fiber is coming along
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